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- /*
- * cpuidle.c - core cpuidle infrastructure
- *
- * (C) 2006-2007 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
- * Shaohua Li <shaohua.li@intel.com>
- * Adam Belay <abelay@novell.com>
- *
- * This code is licenced under the GPL.
- */
- #include <linux/clockchips.h>
- #include <linux/kernel.h>
- #include <linux/mutex.h>
- #include <linux/sched.h>
- #include <linux/notifier.h>
- #include <linux/pm_qos.h>
- #include <linux/cpu.h>
- #include <linux/cpuidle.h>
- #include <linux/ktime.h>
- #include <linux/hrtimer.h>
- #include <linux/module.h>
- #include <linux/suspend.h>
- #include <linux/tick.h>
- #include <trace/events/power.h>
- #include "cpuidle.h"
- DEFINE_PER_CPU(struct cpuidle_device *, cpuidle_devices);
- DEFINE_PER_CPU(struct cpuidle_device, cpuidle_dev);
- DEFINE_MUTEX(cpuidle_lock);
- LIST_HEAD(cpuidle_detected_devices);
- static int enabled_devices;
- static int off __read_mostly;
- static int initialized __read_mostly;
- int cpuidle_disabled(void)
- {
- return off;
- }
- void disable_cpuidle(void)
- {
- off = 1;
- }
- bool cpuidle_not_available(struct cpuidle_driver *drv,
- struct cpuidle_device *dev)
- {
- return off || !initialized || !drv || !dev || !dev->enabled;
- }
- /**
- * cpuidle_play_dead - cpu off-lining
- *
- * Returns in case of an error or no driver
- */
- int cpuidle_play_dead(void)
- {
- struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices);
- struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
- int i;
- if (!drv)
- return -ENODEV;
- /* Find lowest-power state that supports long-term idle */
- for (i = drv->state_count - 1; i >= 0; i--)
- if (drv->states[i].enter_dead)
- return drv->states[i].enter_dead(dev, i);
- return -ENODEV;
- }
- static int find_deepest_state(struct cpuidle_driver *drv,
- struct cpuidle_device *dev,
- unsigned int max_latency,
- unsigned int forbidden_flags,
- bool freeze)
- {
- unsigned int latency_req = 0;
- int i, ret = 0;
- for (i = 1; i < drv->state_count; i++) {
- struct cpuidle_state *s = &drv->states[i];
- struct cpuidle_state_usage *su = &dev->states_usage[i];
- if (s->disabled || su->disable || s->exit_latency <= latency_req
- || s->exit_latency > max_latency
- || (s->flags & forbidden_flags)
- || (freeze && !s->enter_freeze))
- continue;
- latency_req = s->exit_latency;
- ret = i;
- }
- return ret;
- }
- #ifdef CONFIG_SUSPEND
- /**
- * cpuidle_find_deepest_state - Find the deepest available idle state.
- * @drv: cpuidle driver for the given CPU.
- * @dev: cpuidle device for the given CPU.
- */
- int cpuidle_find_deepest_state(struct cpuidle_driver *drv,
- struct cpuidle_device *dev)
- {
- return find_deepest_state(drv, dev, UINT_MAX, 0, false);
- }
- static void enter_freeze_proper(struct cpuidle_driver *drv,
- struct cpuidle_device *dev, int index)
- {
- /*
- * trace_suspend_resume() called by tick_freeze() for the last CPU
- * executing it contains RCU usage regarded as invalid in the idle
- * context, so tell RCU about that.
- */
- RCU_NONIDLE(tick_freeze());
- /*
- * The state used here cannot be a "coupled" one, because the "coupled"
- * cpuidle mechanism enables interrupts and doing that with timekeeping
- * suspended is generally unsafe.
- */
- stop_critical_timings();
- drv->states[index].enter_freeze(dev, drv, index);
- WARN_ON(!irqs_disabled());
- /*
- * timekeeping_resume() that will be called by tick_unfreeze() for the
- * first CPU executing it calls functions containing RCU read-side
- * critical sections, so tell RCU about that.
- */
- RCU_NONIDLE(tick_unfreeze());
- start_critical_timings();
- }
- /**
- * cpuidle_enter_freeze - Enter an idle state suitable for suspend-to-idle.
- * @drv: cpuidle driver for the given CPU.
- * @dev: cpuidle device for the given CPU.
- *
- * If there are states with the ->enter_freeze callback, find the deepest of
- * them and enter it with frozen tick.
- */
- int cpuidle_enter_freeze(struct cpuidle_driver *drv, struct cpuidle_device *dev)
- {
- int index;
- /*
- * Find the deepest state with ->enter_freeze present, which guarantees
- * that interrupts won't be enabled when it exits and allows the tick to
- * be frozen safely.
- */
- index = find_deepest_state(drv, dev, UINT_MAX, 0, true);
- if (index > 0)
- enter_freeze_proper(drv, dev, index);
- return index;
- }
- #endif /* CONFIG_SUSPEND */
- /**
- * cpuidle_enter_state - enter the state and update stats
- * @dev: cpuidle device for this cpu
- * @drv: cpuidle driver for this cpu
- * @index: index into the states table in @drv of the state to enter
- */
- int cpuidle_enter_state(struct cpuidle_device *dev, struct cpuidle_driver *drv,
- int index)
- {
- int entered_state;
- struct cpuidle_state *target_state = &drv->states[index];
- bool broadcast = !!(target_state->flags & CPUIDLE_FLAG_TIMER_STOP);
- ktime_t time_start, time_end;
- s64 diff;
- /*
- * Tell the time framework to switch to a broadcast timer because our
- * local timer will be shut down. If a local timer is used from another
- * CPU as a broadcast timer, this call may fail if it is not available.
- */
- if (broadcast && tick_broadcast_enter()) {
- index = find_deepest_state(drv, dev, target_state->exit_latency,
- CPUIDLE_FLAG_TIMER_STOP, false);
- if (index < 0) {
- default_idle_call();
- return -EBUSY;
- }
- target_state = &drv->states[index];
- broadcast = false;
- }
- /* Take note of the planned idle state. */
- sched_idle_set_state(target_state);
- trace_cpu_idle_rcuidle(index, dev->cpu);
- time_start = ns_to_ktime(local_clock());
- stop_critical_timings();
- entered_state = target_state->enter(dev, drv, index);
- start_critical_timings();
- time_end = ns_to_ktime(local_clock());
- trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, dev->cpu);
- /* The cpu is no longer idle or about to enter idle. */
- sched_idle_set_state(NULL);
- if (broadcast) {
- if (WARN_ON_ONCE(!irqs_disabled()))
- local_irq_disable();
- tick_broadcast_exit();
- }
- if (!cpuidle_state_is_coupled(drv, index))
- local_irq_enable();
- diff = ktime_us_delta(time_end, time_start);
- if (diff > INT_MAX)
- diff = INT_MAX;
- dev->last_residency = (int) diff;
- if (entered_state >= 0) {
- /* Update cpuidle counters */
- /* This can be moved to within driver enter routine
- * but that results in multiple copies of same code.
- */
- dev->states_usage[entered_state].time += dev->last_residency;
- dev->states_usage[entered_state].usage++;
- } else {
- dev->last_residency = 0;
- }
- return entered_state;
- }
- /**
- * cpuidle_select - ask the cpuidle framework to choose an idle state
- *
- * @drv: the cpuidle driver
- * @dev: the cpuidle device
- *
- * Returns the index of the idle state. The return value must not be negative.
- */
- int cpuidle_select(struct cpuidle_driver *drv, struct cpuidle_device *dev)
- {
- return cpuidle_curr_governor->select(drv, dev);
- }
- /**
- * cpuidle_enter - enter into the specified idle state
- *
- * @drv: the cpuidle driver tied with the cpu
- * @dev: the cpuidle device
- * @index: the index in the idle state table
- *
- * Returns the index in the idle state, < 0 in case of error.
- * The error code depends on the backend driver
- */
- int cpuidle_enter(struct cpuidle_driver *drv, struct cpuidle_device *dev,
- int index)
- {
- if (cpuidle_state_is_coupled(drv, index))
- return cpuidle_enter_state_coupled(dev, drv, index);
- return cpuidle_enter_state(dev, drv, index);
- }
- /**
- * cpuidle_reflect - tell the underlying governor what was the state
- * we were in
- *
- * @dev : the cpuidle device
- * @index: the index in the idle state table
- *
- */
- void cpuidle_reflect(struct cpuidle_device *dev, int index)
- {
- if (cpuidle_curr_governor->reflect && index >= 0)
- cpuidle_curr_governor->reflect(dev, index);
- }
- /**
- * cpuidle_install_idle_handler - installs the cpuidle idle loop handler
- */
- void cpuidle_install_idle_handler(void)
- {
- if (enabled_devices) {
- /* Make sure all changes finished before we switch to new idle */
- smp_wmb();
- initialized = 1;
- }
- }
- /**
- * cpuidle_uninstall_idle_handler - uninstalls the cpuidle idle loop handler
- */
- void cpuidle_uninstall_idle_handler(void)
- {
- if (enabled_devices) {
- initialized = 0;
- wake_up_all_idle_cpus();
- }
- /*
- * Make sure external observers (such as the scheduler)
- * are done looking at pointed idle states.
- */
- synchronize_rcu();
- }
- /**
- * cpuidle_pause_and_lock - temporarily disables CPUIDLE
- */
- void cpuidle_pause_and_lock(void)
- {
- mutex_lock(&cpuidle_lock);
- cpuidle_uninstall_idle_handler();
- }
- EXPORT_SYMBOL_GPL(cpuidle_pause_and_lock);
- /**
- * cpuidle_resume_and_unlock - resumes CPUIDLE operation
- */
- void cpuidle_resume_and_unlock(void)
- {
- cpuidle_install_idle_handler();
- mutex_unlock(&cpuidle_lock);
- }
- EXPORT_SYMBOL_GPL(cpuidle_resume_and_unlock);
- /* Currently used in suspend/resume path to suspend cpuidle */
- void cpuidle_pause(void)
- {
- mutex_lock(&cpuidle_lock);
- cpuidle_uninstall_idle_handler();
- mutex_unlock(&cpuidle_lock);
- }
- /* Currently used in suspend/resume path to resume cpuidle */
- void cpuidle_resume(void)
- {
- mutex_lock(&cpuidle_lock);
- cpuidle_install_idle_handler();
- mutex_unlock(&cpuidle_lock);
- }
- /**
- * cpuidle_enable_device - enables idle PM for a CPU
- * @dev: the CPU
- *
- * This function must be called between cpuidle_pause_and_lock and
- * cpuidle_resume_and_unlock when used externally.
- */
- int cpuidle_enable_device(struct cpuidle_device *dev)
- {
- int ret;
- struct cpuidle_driver *drv;
- if (!dev)
- return -EINVAL;
- if (dev->enabled)
- return 0;
- drv = cpuidle_get_cpu_driver(dev);
- if (!drv || !cpuidle_curr_governor)
- return -EIO;
- if (!dev->registered)
- return -EINVAL;
- ret = cpuidle_add_device_sysfs(dev);
- if (ret)
- return ret;
- if (cpuidle_curr_governor->enable &&
- (ret = cpuidle_curr_governor->enable(drv, dev)))
- goto fail_sysfs;
- smp_wmb();
- dev->enabled = 1;
- enabled_devices++;
- return 0;
- fail_sysfs:
- cpuidle_remove_device_sysfs(dev);
- return ret;
- }
- EXPORT_SYMBOL_GPL(cpuidle_enable_device);
- /**
- * cpuidle_disable_device - disables idle PM for a CPU
- * @dev: the CPU
- *
- * This function must be called between cpuidle_pause_and_lock and
- * cpuidle_resume_and_unlock when used externally.
- */
- void cpuidle_disable_device(struct cpuidle_device *dev)
- {
- struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
- if (!dev || !dev->enabled)
- return;
- if (!drv || !cpuidle_curr_governor)
- return;
- dev->enabled = 0;
- if (cpuidle_curr_governor->disable)
- cpuidle_curr_governor->disable(drv, dev);
- cpuidle_remove_device_sysfs(dev);
- enabled_devices--;
- }
- EXPORT_SYMBOL_GPL(cpuidle_disable_device);
- static void __cpuidle_unregister_device(struct cpuidle_device *dev)
- {
- struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
- list_del(&dev->device_list);
- per_cpu(cpuidle_devices, dev->cpu) = NULL;
- module_put(drv->owner);
- dev->registered = 0;
- }
- static void __cpuidle_device_init(struct cpuidle_device *dev)
- {
- memset(dev->states_usage, 0, sizeof(dev->states_usage));
- dev->last_residency = 0;
- }
- /**
- * __cpuidle_register_device - internal register function called before register
- * and enable routines
- * @dev: the cpu
- *
- * cpuidle_lock mutex must be held before this is called
- */
- static int __cpuidle_register_device(struct cpuidle_device *dev)
- {
- int ret;
- struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
- if (!try_module_get(drv->owner))
- return -EINVAL;
- per_cpu(cpuidle_devices, dev->cpu) = dev;
- list_add(&dev->device_list, &cpuidle_detected_devices);
- ret = cpuidle_coupled_register_device(dev);
- if (ret)
- __cpuidle_unregister_device(dev);
- else
- dev->registered = 1;
- return ret;
- }
- /**
- * cpuidle_register_device - registers a CPU's idle PM feature
- * @dev: the cpu
- */
- int cpuidle_register_device(struct cpuidle_device *dev)
- {
- int ret = -EBUSY;
- if (!dev)
- return -EINVAL;
- mutex_lock(&cpuidle_lock);
- if (dev->registered)
- goto out_unlock;
- __cpuidle_device_init(dev);
- ret = __cpuidle_register_device(dev);
- if (ret)
- goto out_unlock;
- ret = cpuidle_add_sysfs(dev);
- if (ret)
- goto out_unregister;
- ret = cpuidle_enable_device(dev);
- if (ret)
- goto out_sysfs;
- cpuidle_install_idle_handler();
- out_unlock:
- mutex_unlock(&cpuidle_lock);
- return ret;
- out_sysfs:
- cpuidle_remove_sysfs(dev);
- out_unregister:
- __cpuidle_unregister_device(dev);
- goto out_unlock;
- }
- EXPORT_SYMBOL_GPL(cpuidle_register_device);
- /**
- * cpuidle_unregister_device - unregisters a CPU's idle PM feature
- * @dev: the cpu
- */
- void cpuidle_unregister_device(struct cpuidle_device *dev)
- {
- if (!dev || dev->registered == 0)
- return;
- cpuidle_pause_and_lock();
- cpuidle_disable_device(dev);
- cpuidle_remove_sysfs(dev);
- __cpuidle_unregister_device(dev);
- cpuidle_coupled_unregister_device(dev);
- cpuidle_resume_and_unlock();
- }
- EXPORT_SYMBOL_GPL(cpuidle_unregister_device);
- /**
- * cpuidle_unregister: unregister a driver and the devices. This function
- * can be used only if the driver has been previously registered through
- * the cpuidle_register function.
- *
- * @drv: a valid pointer to a struct cpuidle_driver
- */
- void cpuidle_unregister(struct cpuidle_driver *drv)
- {
- int cpu;
- struct cpuidle_device *device;
- for_each_cpu(cpu, drv->cpumask) {
- device = &per_cpu(cpuidle_dev, cpu);
- cpuidle_unregister_device(device);
- }
- cpuidle_unregister_driver(drv);
- }
- EXPORT_SYMBOL_GPL(cpuidle_unregister);
- /**
- * cpuidle_register: registers the driver and the cpu devices with the
- * coupled_cpus passed as parameter. This function is used for all common
- * initialization pattern there are in the arch specific drivers. The
- * devices is globally defined in this file.
- *
- * @drv : a valid pointer to a struct cpuidle_driver
- * @coupled_cpus: a cpumask for the coupled states
- *
- * Returns 0 on success, < 0 otherwise
- */
- int cpuidle_register(struct cpuidle_driver *drv,
- const struct cpumask *const coupled_cpus)
- {
- int ret, cpu;
- struct cpuidle_device *device;
- ret = cpuidle_register_driver(drv);
- if (ret) {
- pr_err("failed to register cpuidle driver\n");
- return ret;
- }
- for_each_cpu(cpu, drv->cpumask) {
- device = &per_cpu(cpuidle_dev, cpu);
- device->cpu = cpu;
- #ifdef CONFIG_ARCH_NEEDS_CPU_IDLE_COUPLED
- /*
- * On multiplatform for ARM, the coupled idle states could be
- * enabled in the kernel even if the cpuidle driver does not
- * use it. Note, coupled_cpus is a struct copy.
- */
- if (coupled_cpus)
- device->coupled_cpus = *coupled_cpus;
- #endif
- ret = cpuidle_register_device(device);
- if (!ret)
- continue;
- pr_err("Failed to register cpuidle device for cpu%d\n", cpu);
- cpuidle_unregister(drv);
- break;
- }
- return ret;
- }
- EXPORT_SYMBOL_GPL(cpuidle_register);
- #ifdef CONFIG_SMP
- /*
- * This function gets called when a part of the kernel has a new latency
- * requirement. This means we need to get all processors out of their C-state,
- * and then recalculate a new suitable C-state. Just do a cross-cpu IPI; that
- * wakes them all right up.
- */
- static int cpuidle_latency_notify(struct notifier_block *b,
- unsigned long l, void *v)
- {
- wake_up_all_idle_cpus();
- return NOTIFY_OK;
- }
- static struct notifier_block cpuidle_latency_notifier = {
- .notifier_call = cpuidle_latency_notify,
- };
- static inline void latency_notifier_init(struct notifier_block *n)
- {
- pm_qos_add_notifier(PM_QOS_CPU_DMA_LATENCY, n);
- }
- #else /* CONFIG_SMP */
- #define latency_notifier_init(x) do { } while (0)
- #endif /* CONFIG_SMP */
- /**
- * cpuidle_init - core initializer
- */
- static int __init cpuidle_init(void)
- {
- int ret;
- if (cpuidle_disabled())
- return -ENODEV;
- ret = cpuidle_add_interface(cpu_subsys.dev_root);
- if (ret)
- return ret;
- latency_notifier_init(&cpuidle_latency_notifier);
- return 0;
- }
- module_param(off, int, 0444);
- core_initcall(cpuidle_init);
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